1. Field of the Invention
The present invention relates to a clocking system that is provided with a magnetic member to be installed at a certain place and a clocking apparatus having a magnetic sensor and controlling the clocking operation on the basis of an external magnetic field from a magnetic member that is detected by the magnetic sensor.
2. Description of the Related Art
For example, a clocking system having a magnetic member and a magnetic sensor as disclosed in Japanese Patent Application Laying Open (KOKAI) 8-122563 has been conventionally known. In this clocking system, when the magnetic sensor detects a predetermined strength of a magnetic field, namely, when the magnetic sensor detects an external magnetic field from the magnetic member, the start and the termination operation of clocking are controlled. This magnetic member is embedded at a certain place (a start/goal position or a position for measuring a traveling time of a section) of a track of a circuit where a vehicle with the magnetic sensor attached is traveling. The magnetic sensor comprises a hole element and it is attached at a bottom surface of the vehicle. If the vehicle passes through the certain place where the magnetic member is embedded, the magnetic sensor attached to the vehicle may detect the external magnetic field from the magnetic member. On the bases of this detection of the external magnetic field by this magnetic sensor, the start and the termination operation of clocking are controlled so that the traveling time of the vehicle is clocked.
In the case of the magnetic member embedded in the track of the circuit and the magnetic sensor attached to the vehicle traveling on this track disclosed in this patent application, under the normal traveling condition of the vehicle, it is possible to maintain a narrow distance range between the magnetic member and the magnetic sensor. For example, at a normal traveling condition, the magnetic sensor attached to the vehicle can be maintained in a distance range within 15 cm or the like on a surface of the track. If the magnetic sensor is located in a range of a short distance from the magnetic member in this way, the magnetic sensor can detect the external magnetic field from the magnetic member.
However, when the vehicle runs on the obstruction, the vehicle may depart from the surface of the track and this may result in increase of a distance between the magnetic member and the magnetic sensor. Normally, the external magnetic field from the magnetic member may be rapidly decreased in accordance with a distance form the magnetic member. Thus, if a distance between the magnetic member and the magnetic sensor increases, the magnetic sensor cannot detect the external magnetic field from the magnetic member.
In addition, when a target object with the magnetic sensor installed passes through a place where the magnetic member is embedded, the target object to be clocked not may be a vehicle such as an automobile or the like as in the above mentioned patent application but may be a human being in a clocking system for detecting the external magnetic field from the magnetic member and controlling clocking. For example, this may be a case that a lap time of a certain section and a split time or the like of a competitor are clocked at a competition of a track and field completion, soccer, skate and ski or the like, or while practicing them.
In the above described case, since the external magnetic field from the embedded magnetic member does not reach in the distance, the magnetic sensor is needed to pass through the vicinity of the magnetic member as much as possible in order to detect the external magnetic field of the magnetic member. Therefore, for example, it may be considered that the magnetic sensor is attached to the shoes of the competitor so that the magnetic sensor is brought close to the surface of an athletic field such as a track or the like as much as possible. However, in accordance with the operation of the competitor complied with each competition, the shoes of the competitor to which the magnetic sensor is attached may be detached from the surface of the athletic field such as a track or the like. In such a case, a distance between the magnetic member and the magnetic sensor does not remain constant and the magnetic sensor cannot detect the external magnetic field generated by the magnetic member, and as a result, clocking cannot be performed.
There are some kinds of competitions in which a body portion of the competitor, for example, a waist of the competitor is maintained at a relative constant height from the surface of the athletic field. However, in such a competition, in the case that the magnetic sensor attached to, for example, the waist portion of the competitor passing over the magnetic member that is embedded in the athletic field detects the external magnetic field from the magnetic member, the distance between the magnetic member and the magnetic sensor becomes very long. In such a case, the magnetic sensor is forced to detect the external magnetic field from the magnetic member that is far apart therefrom.
As one method for elongating the distance from the magnetic member that can be detected by the magnetic sensor, a method to raise the sensitivity of the magnetic sensor such as a hole element or the like may be considered. However, if the magnetic sensor having a high sensitivity is used, it can easily detect not only the external magnetic field from the magnetic member to be detected but also the external magnetic field from other members located in a measurement environment. Therefore, a signal on the basis of the magnetic field from other members is also generated, so that the clocking control on the basis of the detection of the external magnetic field from the magnetic member by the magnetic sensor cannot be performed. Accordingly, by using the magnetic sensor having too high sensitivity, it is not possible to perform clocking reliably.
In addition, as an another method, a method may be considered such that a magnetic member is made by a strong magnet so as to make the external magnetic field from the magnetic member stronger. However, if the strong magnet is used, the magnetic members are attracted or repelled with each other by a strong force, or the magnetic members strongly attract various materials including a magnetic body. As a result, risk upon manufacturing such a magnetic member and risk upon installation or removal of such a magnetic member may increase. In addition, when the strong magnet is used, this has a problem such that the magnetic member becomes expensive.
In a clocking system provided with a magnetic member installed at a certain place and a clocking apparatus for controlling the clocking operation on the basis of an external magnetic field from a magnetic member that is detected by a magnetic sensor, there is a problem such that this clocking system should be constructed so that the magnetic member is installed movably in addition to a problem such that a distance from the magnetic member that the above described magnetic sensor can detect should be made longer.
In the other words, the magnetic member is embedded in the track to be clocked and the embedded position is fixed. However, in order to use the clocking system for various applications, it is preferable that the magnetic member can be installed movably and the magnetic member is installed at a required position, in a required competition, and at a required time to clock.
As an aspect of such a movable magnetic member, it may be considered that the magnetic member is not embedded in the track but it is installed under the condition that the magnetic member is upreared. In this mode, the upreared magnetic member is installed freely and movably at a certain place. In this case, the magnetic sensor attached to the competitor passing through a side of the upreared magnetic member may detect the external magnetic field from the upreared magnetic member. In this mode, if the distance from the magnetic member that can be detected by the magnetic sensor is short, the competitor should pass through the edge of the side of the magnetic member. Therefore, the competitor is forced to have an unnatural posture upon passing through the side of the magnetic member. Such an unnatural posture forced to the competitor has an adverse effect on the competition itself and this is removed from an original purpose such that the passing time at the competition is clocked. In addition, due to this unnatural posture and the crash into the magnetic member, the competitor to be clocked may even be in danger.
Also in the case of constructing the magnetic member that is movably installed as being upreared, it is necessary for a detectable distance of the external magnetic field from the magnetic member by the magnetic sensor to be longer.
A clocking system has been desired such that the magnetic sensor can detect the external magnetic field from the magnetic member that is rather far apart therefrom without increasing the sensitivity of the magnetic sensor excessively and without making the magnet constructing the magnetic member strong excessively. Further, in such a clocking system, it has been desired that the magnetic member can be installed movably.